Metal frame and method for manufacturing the same

ABSTRACT

A method for manufacturing a metal frame, such as a tractor cab frame, that can reduce scrap material, simplify the manufacturing process, improve the structural integrity of the frame, and eliminate the use of overlapping joint areas. According to one embodiment, the manufacturing method includes the steps of: blanking a number of individual metal segments, joining the individual metal segments together to form a welded blank assembly, stamping the welded blank assembly to form a stamping assembly that includes the desired perimeter, and forming the stamping assembly by bending the stamping assembly into the final shape of the three-dimensional metal frame. The resultant metal frame preferably includes at least one metal segment that is shared between adjacent sides of the structure and is bent along its length to form a smooth transitioning corner lacking overlapping joint areas.

REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Ser. No. 60/760,273 filed on Jan. 19, 2006, the entire contents of which are incorporated herein.

FIELD OF INVENTION

The present invention generally relates to a method for manufacturing a metal frame, and more particularly, to a manufacturing method that utilizes a combination of blanking, welding, stamping and forming steps to improve the process and the structure produced thereby.

BACKGROUND OF THE INVENTION

A number of different manufacturing processes have been developed over the years that produce various types of metal structures, such as frames and other structural components oftentimes found in vehicles, agricultural machinery, construction machinery, lawn and garden equipment, etc.

With reference to FIGS. 1A-B, there is shown a diagrammatic illustration of one example of a prior art method for manufacturing part of a tractor cab frame 8 that generally includes a front windshield panel 10 and a pair of side window panels 12 and 14. According to this particular method, each of the panels is first blanked from a sheet metal piece, which results in the basic rectangular panels or frames 10-14 and interior scrap pieces or offal 20-24 shown in FIG. 1A. After the blanked panels 10-14 have been formed, they are loaded into a stamping press and are individually stamped into a predetermined shape. Finally, the three blanked and stamped panels are brought together and joined by some combination of spot welds, seam welds, adhesives, rivets, etc. so that they form part of a finished, three-dimensional tractor cab frame 8. Although this type of method has been extensively used in the industry, there are certain drawbacks. For example, the above-described method produces both excess scrap material and joint overlap areas. An example of a joint overlap area 26 is shown in FIG. 1B, and includes an edge of front windshield panel 10 that is bent behind an overlapping edge of side window panel 14. Stamping or forming panels 10-14 before joining them together can result in greater tolerance discrepancies and increased gaps between the panels. Thus, it is sometimes necessary to seal overlap area 26 to prevent leaks or to fill it in order to provide a smooth, flush surface before the frame can be painted.

Turning now to FIGS. 2A-B, there is shown a diagrammatic illustration of another known method for forming part of a tractor cab frame 28 that includes a front windshield panel 30 and side window panels 32 and 34. Instead of being stamped from a single piece of sheet metal as with the previous method, each of the panels 30-34 is comprised of four individual rectangular segments or legs making up a different side of the panel. Because of the similarity between panels 30-34, the following description of front windshield panel 30 applies equally to side window panels 32 and 34. According to this method, four individual segments 40-46 are first blanked from a sheet metal piece. Next, segments 40-46 are laser welded, mash-seam welded or otherwise joined to one another so that the rectangular-shaped panel 30 of FIG. 2A is formed. At this point, the three separate rectangular panels 30-34, each of which includes four welded segments, are stamped into their required shape. Finally, the three blanked, welded and stamped panels 30-34 are brought together and attached to one another by one or more of the joining processes mentioned above. This results in part of a finished, three-dimensional tractor cab frame 28. Although this process reduces the excess scrap center material produced by the previous process, it still produces several joint overlap areas 48, as explained above.

SUMMARY OF THE INVENTION

According to one embodiment, there is provided a method for manufacturing a metal frame having at least first and second sides. The method generally comprises the steps of: (a) producing a plurality of individual metal segments; (b) welding the plurality of individual metal segments together to form a welded blank assembly; (c) stamping the welded blank assembly to form a stamping assembly; and (d) forming the stamping assembly into the metal frame by bending the first and second sides so that they are aligned relative to one another.

According to another embodiment, there is provided a method for manufacturing a metal frame having at least first and second sides. The method generally comprises the steps of: (a) blanking a plurality of individual metal segments generally in the form of simple shapes so that they can be tightly arranged on a piece of sheet metal stock; (b) welding the plurality of individual metal segments to form a welded blank assembly, wherein the welded blank assembly includes segments of the first side and segments of the second side joined together in an edge-to-edge arrangement that lacks overlapping joint areas; (c) stamping the welded blank assembly to form a stamping assembly that has a different perimeter than the welded blank assembly; and (d) forming the stamping assembly into the metal frame by bending the stamping assembly so that the first and second sides are joined by a shared metal segment that is bent along its length to form a corner having a smooth transition.

According to another embodiment, there is provided a metal frame for use with a piece of movable equipment. The metal frame generally comprises: a first side window panel having a first plurality of blanked metal segments welded together; a second side window panel having a second plurality of blanked metal segments welded together; and a center windshield panel having a third plurality of blanked metal segments welded together. The first side window panel and center windshield panel share a first elongated vertical pillar that is bent along its length to form a first corner, and the second side window panel and center windshield panel share a second elongated vertical pillar that is bent along its length to form a second corner.

DESCRIPTION OF THE DRAWINGS

A preferred exemplary embodiment of the invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and wherein:

FIGS. 1A-2B are diagrammatic illustrations of known methods for forming three-dimensional metal structures;

FIG. 3 is an example of part of a tractor cab frame formed by an embodiment of the present method;

FIG. 4 is a welded blank assembly of the part of the tractor cab frame of FIG. 3, following blanking and welding steps of the present method; and

FIG. 5 is a stamping assembly of the part of the tractor cab frame of FIG. 3 following blanking, welding and stamping steps of the present method.

DESCRIPTION OF A PREFERRED EMBODIMENT

The following description is directed to an improved method for manufacturing a metal frame, such as a frame or other structural component found on a vehicle or piece of agricultural equipment. This method generally reduces the production of scrap material or offal, decreases the number of manufacturing steps, and eliminates the use of certain overlapping joint areas, to name but a few of its attributes. With reference to FIG. 3, there is shown an example of a three-dimensional metal frame 50, in this case part of a tractor cab frame, that can be produced by the present method and generally includes a front windshield panel 52 and side window panels 54, 56. It should be appreciated, however, that the present method can be used to generate one of a number of different three-dimensional metal structures and is not limited to the particular tractor cab frame 50 shown here. For instance, the present method could be used to manufacture certain body components, chassis parts, frames and other structural components for automobiles, trucks, recreation vehicles (RVs), agricultural machinery, construction machinery, and lawn and garden equipment, to name but a few possibilities.

According to a first step of the present method, a number of individual metal segments 60-78 are first blanked from one or more pieces of sheet metal stock. The sheet metal stock can be provided in the form of coils, flat panels, or any other suitable form known in the art, and is preferably made of steel, aluminum, or alloys thereof. Of course, segments 60-78 can all have a uniform thickness or they can be formed from sheet metal stock of varying thicknesses, depending on the structural requirements of the different segments. For example, if one of the metal segments is a vertical pillar that when assembled carries the weight of a door, it may be desirable to use thicker sheet metal than is used on other non-weight bearing segments (sometimes referred to as a tailor-welded blank). Each of the segments 60-78 shown in FIG. 4 is in the form of a simple geometric shape, which can include rectangles, trapezoids, and other polygons lacking complex curves. By first blanking the segments in a simple shape, as opposed to initially forming them in the more complex shape that the segments will ultimately assume, it allows the segments to be nested or tightly arranged on the sheet metal such that a single blanking operation creates multiple segments and minimizes the amount of scrap material or offal produced thereby. Furthermore, the simple shape configuration of segments 60-78 simplifies the subsequent joining process, as all of the abutting segments are aligned at 90 angles to one another. It should be recognized that while rectangular segments are shown in this exemplary embodiment, other non-rectangular segments like trapezoids and other polygons can also be used. Also, alternative methods, other than blanking, could be used for making the individual metal segments; examples of these other methods include, but are not limited to, laser cutting, water-jet cutting, roll-forming and extruding.

Once the blanking step is completed, segments 60-78 are laid out in the desired arrangement and are joined together via laser welding, mash seam welding, butt welding or any other appropriate welding or joining technique known in the art. This results in the generally planar, unitary welded blank assembly 80 shown in FIG. 4, which includes segments not only for a front windshield panel, but also segments for both side window panels. In the prior art methods previously described, each of the different sides of the tractor cab frame were produced separately and were then assembled together at the end of the process. Conversely, the present method assembles multiple sides of the tractor cab together in the form of a single welded blank assembly 80, and then performs the necessary stamping and forming operations. In addition to improvements in the efficiency of the process, welded blank assembly 80 also reduces material costs by sharing certain segments between the different panels. For instance, segment 66 is a vertical pillar that is shared between the center windshield panel and the side window panel on the left, and segment 72 is a vertical pillar shared by the center windshield panel and the side window panel on the right. Furthermore, the welded blank assembly 80 lacks overlapping joint areas between metal segments because the various metal segments are joined together in an edge-to-edge arrangement. Although this particular embodiment only shows welded joints aligned in a vertical orientation, it is possible to have horizontal, angular, curved, and other non-vertical weld joints as well.

Next, welded blank assembly 80 is loaded into a stamping press and is stamped to provide it with a different perimeter and three-dimensional shape, which results in a stamping assembly 88. With reference to FIG. 5, there is shown the original perimeter 90 of welded blank assembly 80 before the stamping operation, and a new, more complex perimeter 92 of stamping assembly 88 after it is stamped. Of course, welded blank assembly 80 is preferably designed so that the amount of excess material trimmed off during the stamping operation is kept to a minimum; that is, the amount of material between perimeters 90 and 92. In addition to forming a new perimeter, the stamping operation provides stamping assembly 88 with all of the contours, creases, valleys, edges or other three-dimensional features needed for the final structure. Thus, while stamping assembly 88 may be generally flat, it preferably contains the three-dimensional aspects previously cited. The amount of three-dimensionality primarily depends on the particular application in which it is used.

Lastly, stamping assembly 88 is loaded into a metal forming machine so that it can be formed into the three-dimensional tractor cab frame 50 shown in FIG. 3. As previously indicated, stamping assembly 88 already includes all of the segments for front windshield panel 52 and side window panels 54 and 56, however, they are all part of a single, generally flat stamping assembly. Thus, the present metal forming step simply bends the stamping assembly into the three-sided configuration shown in FIG. 3. In this particular case, two 90° bends are needed for tractor cab frame 50 to have three generally perpendicularly-aligned sides. However, the present method could alternatively be used to form structures having more or less than three sides (two-sided frames, four-sided frames, etc.), form non-90° angles such as acute or obtuse angles, and form the frame by bending it along horizontal, angular, and other non-vertical junctions. As demonstrated by the blowup section of FIG. 3, the tractor cab frame preferably lacks overlapping joints such as those discussed in connection with the prior art. The smooth, flush transition 96 that extends around the corner between center windshield panel 52 and the side window panel 56 is generally the result of segment 72 (FIG. 4) being creased or bent along its length, as opposed to two separate panels being joined together via an overlapping seam. This type of junction between sides of the tractor cab frame can improve structural integrity and manufacturing flexibility, as the bend can be provided with a sharp edge, a radiused edge or any other appropriate configuration. Moreover, the welded junctions between the various segments 60-78 are flush, non-overlapping joints, which tends to cut down on the weight and amount of material and provides a smooth surface from segment to segment, to name but a few qualities. Examples of suitable metal forming equipment include brake and press-brake machines, although other types of equipment could be used as well.

It is to be understood that the foregoing description is not a definition of the invention, but is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

As used in this specification and claims, the terms “for example,” “for instance,” “like,” and “such as,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation. 

1. A method for manufacturing a metal frame having at least first and: second sides, comprising the steps of: (a) producing a plurality of individual metal segments; (b) welding the plurality of individual metal segments together to form a welded blank assembly; (c) stamping the welded blank assembly to form a stamping assembly; and (d) forming the stamping assembly into the metal frame by bending the first and second sides so that they are aligned relative to one another.
 2. The method of claim 1, wherein step (a) further comprises producing the plurality of individual metal segments by blanking them generally in the form of simple shapes so that they can be tightly arranged on a piece of sheet metal stock to minimize the amount of scrap material.
 3. The method of claim 1, wherein step (a) further comprises producing the plurality of individual metal segments from pieces of sheet metal stock of varying thickness so that weight bearing segments of the metal frame can be made from thicker sheet metal than non-weight bearing segments.
 4. The method of claim 1, wherein step (b) further comprises welding the plurality of individual metal segments together so that at least one of the plurality of individual metal segments is shared by both the first and second sides of the metal frame.
 5. The method of claim 4, wherein the at least one shared metal segment is a vertical pillar that is shared by a center windshield panel and a side window panel.
 6. The method of claim 1, wherein step (b) further comprises welding the plurality of individual metal segments together in an edge-to-edge arrangement to form a single welded blank assembly that lacks overlapping joint areas between individual metal segments.
 7. The method of claim 1, wherein step (c) further comprises stamping the welded blank assembly to form a generally flat stamping assembly with a different perimeter and three-dimensional shape than the welded blank assembly.
 8. The method of claim 1, wherein step (d) further comprises forming the stamping assembly into the metal frame by bending the first and second sides so that they are generally perpendicularly-aligned relative to one another.
 9. The method of claim 1, wherein step (d) further comprises forming the stamping assembly into the metal frame by bending the first and second sides of the metal frame so that they are joined by a shared metal segment that is bent along its length to form a corner having a smooth transition.
 10. The method of claim 9, wherein the first and second sides of the metal frame include a center windshield panel and a side window panel, and the shared metal segment is a vertical pillar.
 11. The method of claim 1, wherein the metal frame is part of a tractor cab frame, and first and second sides of the metal frame include a center windshield panel and a side window panel.
 12. A method for manufacturing a metal frame having at least first and second sides, comprising the steps of: (a) blanking a plurality of individual metal segments generally in the form of simple shapes so that they can be tightly arranged on a piece of sheet metal stock to minimize the amount of scrap material produced; (b) welding the plurality of individual metal segments to form a welded blank assembly, wherein the welded blank assembly includes segments of the first side and segments of the second side joined together in an edge-to-edge arrangement that lacks overlapping joint areas; (c) stamping the welded blank assembly to form a stamping assembly that has a different perimeter than the welded blank assembly; and (d) forming the stamping assembly into the metal frame by bending the stamping assembly so that the first and second sides are joined by a shared metal segment that is bent along its length to form a corner having a smooth transition.
 13. The method of claim 12, wherein step (a) further comprises blanking the plurality of individual metal segments from pieces of sheet metal stock of varying thickness so that weight bearing segments of the metal frame can be made from thicker sheet metal than non-weight bearing segments.
 14. The method of claim 12, wherein the metal frame is part of a tractor cab frame, first and second sides of the metal frame include a center windshield panel and a side window panel, and the shared metal segment is a vertical pillar.
 15. A metal frame for use with a piece of movable equipment, comprising: a first side window panel having a first plurality of blanked metal segments that are welded together; a second side window panel having a second plurality of blanked metal segments that are welded together; and a center windshield panel having a third plurality of blanked metal segments that are welded together, wherein the first side window panel and center windshield panel share a first elongated vertical pillar that is bent along its length to form a first corner that extends between the first side window panel and center windshield panel in a smooth transition, and the second side window panel and center windshield panel share a second elongated vertical pillar that is bent along its length to form a second corner that extends between the second side window panel and center windshield panel in a smooth transition. 